UPDATED: 14 June 2015
WOW® stands for Weigh-On-The-Way®. You can set a weight limit for WOW processing up to 500 grams. Any mail piece that exceeds this weight will exit the system as an exception, and must be manually processed.
This setting is typically used when the mailer sets an internal company rule that all mail pieces over a certain weight should be processed with a different carrier, class, or fee.
Your company may have a policy that all mail pieces over 250 grams must be considered for a different class. In this case, you would set the WOW limit to 250 grams, and the system stops you if an overweight piece is detected. If the meter detects a mail piece over 250 grams, the meter shows the prompt, Mail Too Heavy. To continue, you must Press Clear to bypass the error.